From a legal perspective, countries can claim a large exclusive economic zone. So for a seastead to fall outside the realm of government intervention would require it to be more than 200 miles offshore. This is roughly the travel distance from San Francisco to South Lake Tahoe at the border with Nevada. So unless you think that South Lake Tahoe is the perfect location with "easy access to the Bay Area" for your start-up, then Thielandia isn't a good place to go, either.
Worse still, however, there could be no recognition of these seasteads as sovereign territory (they lack actual territory) and little incentive to change this. The "greedy government" question aside, the principle reason to reject seastead sovereignty is simply to prevent the strategic colonization of the ocean. For example, a nation could build a series of minimalist seasteads 24 nautical miles apart and claim territorial sovereignty over them and their adjacent waters. Less than 1,000 of these would be required to close the Pacific to all east-west shipping. That's highly doable in this case but the real threats are in open-but-disputed waters like the South China Sea or strategic outlets; a chain of them which impeded shipping could create a toll opportunity for the creator even without closing a waterway.
Of course, there yet remains the problem of simply trying to evade a country's regulations while doing business primarily, or even entirely, there. Countries take a dim view of this sort of activity and it only survives because complainant countries are unwilling to effectively retaliate against host countries. Again, lacking sovereignty, the seastead would be a legitimate target of a government force. More importantly, it would lack any significant native population and there may be few people not directly involved in this activity. This means that force against them is easier to justify and the seastead itself could easily be destroyed given that all the inhabitants can be repatriated.
To succeed, seasteading needs to be a viable alternative to landsteading. But for the reasons above, it can't be both viable and a real alternative. The moment it becomes a real alternative, it will need to be shut down to prevent very serious problems, thus it become unviable. It can be viable, but only if it is small enough to be ignored. On a more fundamental level, I doubt many people would want to live there given the costs and distance. If anything, the seasteads would mostly become nests of shady pornographers and scamsters, precisely the people who most like to play jurisdictional games now and have the incentive to do so. This would legitimate any retaliation against a seastead, possibly with precedent from smuggling and piracy.
My answer: the success likelihood is near zero.
They actually respond to a lot of this in their FAQ.
An important model for them right now are Cruise lines. The big ones operate with a large degree of autonomy while flying the flag of countries that are most amenable to this and doing business in ports where people like to make money (it turns out, this is a lot of them).
So, the sea steads will fly the flag of a sovereign country and acts of overt aggression against them would be attacks on a sovereign country.
Recently the relatively awesome entrepreneur invested 1.25 million USD into this (seasteading institute website here).
It seems such a wonderful concept, finally somewhere where new forms of government could be tried out. But I'm just wondering how in the world they hope to deal with existing governments since their reaction to any kind of serious alternatives, especially one that either economically or ideologically presented a significant challenge, is bound to not be positive.
I was just wondering what LWer thoughts are on this matter? Also has there been any discussion of seasteading in the past that I've missed? Also I'm wondering if anyone would hazard to perhaps offer a prediction or judge how likley this is to succeed (maybe on predictionbook)?